Sonia Johnson yesterday fought off, at least temporarily, efforts to eject her from the Mormon church because of her controversial support for the Equal Rights Amendment.

The 43-year-old Loudoun County mother of four emerged from nearly five hours in a secret court smiling and making little jokes.

"I'm still a member of the church, for heaven's sake, and here it is 4 o'clock," she said. Five hours earlier she was deeply fearful that the day's session would end her family's five-generation membership in the Church of Jesus Christ of Latter-day Saints.

Technically all she gained in the marathon session with her bishop and his two aides was a two-week postponement of the trial until Dec. 1, plus agreement on the specific charges against her.

The threatened excommunication of an ERA activist from the Mormon church has drawn nationwide attention. Governed by all-male hierarchy, the church has bitterly opposed ERA and has urged members in states where the amendment is up for ratification to actively oppose it.

The issue, however, is not a matter of doctrine, and church spokesmen emphasize that members are free to take their own stands on ERA.

Johnson, a sometime college professor of English, had been instrumental in organizing and directing a group called Mormons for ERA. She has been subject to widespread criticism in the church for her activities.

Last Wednesday night she received a summons to a formal church trail in the bishop's court, a trail which could lead to her excommunication. The trial had been scheduled for 9 a.m. yesterday. Thursday night, she met with the head of her Sterling Park congregation, Bishop Jeffrey Willis, and succeeded in gaining from him a postponement so that she could prepare her defense and summon witnesses.

But at 10 p.m. Friday evening, Willis, who by day is a personnel officer in the CIA, informed her that the trail would begin at 11 a.m. yesterday, giving her 13 hours to get a night's sleep and prepare her defense.

Johnson and some of her Mormon supporters speculated that Willis and his superiors in the church forced the showdown this weekend instead of giving her more time as he has promised because she had discussed her situation with the press.

"I think they are very angry at me because of the press," Johnson said yesterday morning. "It's a real taboo in the church to make public any controversy."

Both Johnson and her husband, Richard, were bitter about the bishop's refusal to state specific charges. They maintained that this cast a shadow on her moral character.

"There is always talk about people being excommunicated in the church," said Richard Johnson, but "99 percent of the time it's on a moral issue -- usually adultery," he said.Refusing to specify charges "is a very nice way of lackening her reputation without saying it," he said.

Today's session, instead of being a trial as has been planned, merely thrashed out a specific formulation of the issues on which she will be tried next month. At the end of the session summarized these issues for the press in the form of questions:

Is she infuencing people in the church to distrust the leadership. "Am I just being purely political or am I attacking the church?" she paraphrased.

Is her ERA stand undermining the teachings of the president of the church, who Mormons believe receives his revelations directly from God?

Is she "knowingly teaching false doctrine?"

Throughout the nearly five hours yesterday Johnson faced the three-man tribunal, known in church terminology as a "love court," alone. Neither her husband nor her attorney were permitted in the room with her. The bishop also refused to permit her to tape record the proceedings. She will, however, be permitted to tape the Dec. 1 session.

Outside the low, rambling, red brick church where yesterday's session took place some 50 supporters -- both men and women -- expressed support for Johnson as well as ERA.

They passed the time chatting quietly in the warm sun, improvising slogans for handprinted placards, and keeping an eye on their children who scampered and played in a huge grassy churchyard.

The gathering was widely ecumenical; only about 8 or 9 of the demonstrators were themselves Marmon.

Several of the placards made invidious comparisons: "Khomeini does not believe in the ERA either," read one.

After Johnson emerged from the trial and held an impromptu press conference the demonstrators called her over to join in a brief ecumenical worship service.